1. Field of the Invention
The present invention relates to a measuring tape, and particularly to a measuring tape having a check device for automatically preventing a ruler from rewinding. As a ruler body is pulled out, it can be stopped automatically. After pressing a press button, the ruler body rewinds by the elastic force of the reed. Thereby, the user operates it by only one hand not to worry about that the hand will be hurt due to rewinding of the ruler body.
2. Description of Related Art
The prior measuring tape is installed with a check device. When the ruler body is pulled out, the ruler body will rewind due to the winding spring in the winding wheel. Therefore, a check device is used to fix the ruler body and prevent the ruler body from rewinding. There are two kinds of check devices. One is a positioning switch which is a press button having two operation stages. As the press button is pressed backwards, the ruler body will be positioned and the winding wheel stops to rotate, while as the press button is pressed forwards, the ruler body will be released and the winding wheel rotates to rewind the ruler body. The second kind is an intermittent operation switch. In this switch, a button is pressed by a finger. When the button is pressed continuously, the winding wheel will be stopped so as not to rotate, while if the button is released, the ruler body will rewind.
In general, only one hand is used to pull the ruler body. In pulling the ruler body, it is necessary to prevent the ruler body from rewinding, otherwise, the measurement work can not be executed. Therefore, the thumb and first finger must pinch the casing of the ruler body tightly, and another hand serves to pull the ruler body continuously. However, it is often that the hand is hurt since the finger and thumb release the ruler body carelessly. This is dangerous to the users, especially, children.
Accordingly, the primary object of the present invention is to provide a measuring tape having a check device for automatically preventing a ruler from rewinding, wherein only after pressing a press button, the ruler body rewinds. Thereby, the user may operate it by only one hand not to worry about that the hand will be hurt due to the rewinding force of the ruler body.
Another object of the present invention is to provide a measuring tape having a check device for automatically preventing a ruler from rewinding, wherein when a user presses a press button by a thumb, a block will push the press plate downwards. Then the press plate presses the resisting plate of the stop claw. Thereby, claw pieces will curl upwards and then separates from the ratchets. Therefore, the rotary wheel will separate from the claw pieces to be in a free condition.
A further object of the present invention is to provide a measuring tape having a check device for automatically preventing a ruler from rewinding, wherein the rewinding of the ruler body is by pressing a button, and thus the operation is simple and safe. Moreover, in rewinding the ruler body, the button can be pressed properly so that the ruler body rewinds slowly.
A further object of the present invention is to provide a measuring tape having a check device for automatically preventing a ruler from rewinding, wherein the user may pull the ruler body rapidly, thereby, the operation time is reduced.
To achieve above objects, the present invention provides measuring tape having a check device for automatically preventing a ruler from rewinding. The check device is installed within the casing and positioned between a winding wheel and a ruler body. The check device comprises a rotary wheel formed by an elastic wheel at a center portion and two ratchets at two sides of the elastic wheel; a guide block formed at a lower end of the rotary wheel and having stop blocks; a stop claw; a driven element installed between the press button and the stop claw; and a press. By above components, the ruler body can be installed between the elastic wheel and the guide block. As the ruler body is pulled out, it can be stopped automatically.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.